drivers/cpuidle/cpuidle-arm.c

   1 /*
   2  * ARM/ARM64 generic CPU idle driver.
   3  *
   4  * Copyright (C) 2014 ARM Ltd.
   5  * Author: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  */
  11
  12 #define pr_fmt(fmt) "CPUidle arm: " fmt
  13
  14 #include <linux/cpuidle.h>
  15 #include <linux/cpumask.h>
  16 #include <linux/cpu_pm.h>
  17 #include <linux/kernel.h>
  18 #include <linux/module.h>
  19 #include <linux/of.h>
  20 #include <linux/slab.h>
  21 #include <linux/topology.h>
  22
  23 #include <asm/cpuidle.h>
  24
  25 #include "dt_idle_states.h"
  26
  27 /*
  28  * arm_enter_idle_state - Programs CPU to enter the specified state
  29  *
  30  * dev: cpuidle device
  31  * drv: cpuidle driver
  32  * idx: state index
  33  *
  34  * Called from the CPUidle framework to program the device to the
  35  * specified target state selected by the governor.
  36  */
  37 static int arm_enter_idle_state(struct cpuidle_device *dev,
  38                                 struct cpuidle_driver *drv, int idx)
  39 {
  40         /*
  41          * Pass idle state index to arm_cpuidle_suspend which in turn
  42          * will call the CPU ops suspend protocol with idle index as a
  43          * parameter.
  44          */
  45         return CPU_PM_CPU_IDLE_ENTER(arm_cpuidle_suspend, idx);
  46 }
  47
  48 static struct cpuidle_driver arm_idle_driver __initdata = {
  49         .name = "arm_idle",
  50         .owner = THIS_MODULE,
  51         /*
  52          * State at index 0 is standby wfi and considered standard
  53          * on all ARM platforms. If in some platforms simple wfi
  54          * can't be used as "state 0", DT bindings must be implemented
  55          * to work around this issue and allow installing a special
  56          * handler for idle state index 0.
  57          */
  58         .states[0] = {
  59                 .enter                  = arm_enter_idle_state,
  60                 .exit_latency           = 1,
  61                 .target_residency       = 1,
  62                 .power_usage            = UINT_MAX,
  63                 .name                   = "WFI",
  64                 .desc                   = "ARM WFI",
  65         }
  66 };
  67
  68 static const struct of_device_id arm_idle_state_match[] __initconst = {
  69         { .compatible = "arm,idle-state",
  70           .data = arm_enter_idle_state },
  71         { },
  72 };
  73
  74 /*
  75  * arm_idle_init_cpu
  76  *
  77  * Registers the arm specific cpuidle driver with the cpuidle
  78  * framework. It relies on core code to parse the idle states
  79  * and initialize them using driver data structures accordingly.
  80  */
  81 static int __init arm_idle_init_cpu(int cpu)
  82 {
  83         int ret;
  84         struct cpuidle_driver *drv;
  85         struct cpuidle_device *dev;
  86
  87         drv = kmemdup(&arm_idle_driver, sizeof(*drv), GFP_KERNEL);
  88         if (!drv)
  89                 return -ENOMEM;
  90
  91         drv->cpumask = (struct cpumask *)cpumask_of(cpu);
  92
  93         /*
  94          * Initialize idle states data, starting at index 1.  This
  95          * driver is DT only, if no DT idle states are detected (ret
  96          * == 0) let the driver initialization fail accordingly since
  97          * there is no reason to initialize the idle driver if only
  98          * wfi is supported.
  99          */
 100         ret = dt_init_idle_driver(drv, arm_idle_state_match, 1);
 101         if (ret <= 0) {
 102                 ret = ret ? : -ENODEV;
 103                 goto out_kfree_drv;
 104         }
 105
 106         /*
 107          * Call arch CPU operations in order to initialize
 108          * idle states suspend back-end specific data
 109          */
 110         ret = arm_cpuidle_init(cpu);
 111
 112         /*
 113          * Allow the initialization to continue for other CPUs, if the reported
 114          * failure is a HW misconfiguration/breakage (-ENXIO).
 115          */
 116         if (ret) {
 117                 pr_err("CPU %d failed to init idle CPU ops\n", cpu);
 118                 ret = ret == -ENXIO ? 0 : ret;
 119                 goto out_kfree_drv;
 120         }
 121
 122         ret = cpuidle_register_driver(drv);
 123         if (ret) {
 124                 if (ret != -EBUSY)
 125                         pr_err("Failed to register cpuidle driver\n");
 126                 goto out_kfree_drv;
 127         }
 128
 129         dev = kzalloc(sizeof(*dev), GFP_KERNEL);
 130         if (!dev) {
 131                 ret = -ENOMEM;
 132                 goto out_unregister_drv;
 133         }
 134         dev->cpu = cpu;
 135
 136         ret = cpuidle_register_device(dev);
 137         if (ret) {
 138                 pr_err("Failed to register cpuidle device for CPU %d\n",
 139                        cpu);
 140                 goto out_kfree_dev;
 141         }
 142
 143         return 0;
 144
 145 out_kfree_dev:
 146         kfree(dev);
 147 out_unregister_drv:
 148         cpuidle_unregister_driver(drv);
 149 out_kfree_drv:
 150         kfree(drv);
 151         return ret;
 152 }
 153
 154 /*
 155  * arm_idle_init - Initializes arm cpuidle driver
 156  *
 157  * Initializes arm cpuidle driver for all CPUs, if any CPU fails
 158  * to register cpuidle driver then rollback to cancel all CPUs
 159  * registeration.
 160  */
 161 static int __init arm_idle_init(void)
 162 {
 163         int cpu, ret;
 164         struct cpuidle_driver *drv;
 165         struct cpuidle_device *dev;
 166
 167         for_each_possible_cpu(cpu) {
 168                 ret = arm_idle_init_cpu(cpu);
 169                 if (ret)
 170                         goto out_fail;
 171         }
 172
 173         return 0;
 174
 175 out_fail:
 176         while (--cpu >= 0) {
 177                 dev = per_cpu(cpuidle_devices, cpu);
 178                 drv = cpuidle_get_cpu_driver(dev);
 179                 cpuidle_unregister_device(dev);
 180                 cpuidle_unregister_driver(drv);
 181                 kfree(dev);
 182                 kfree(drv);
 183         }
 184
 185         return ret;
 186 }
 187 device_initcall(arm_idle_init);